Wind turbine wake vortex influence on safety of small rotorcraft

Abstract

The wake vortex of lifting surfaces such as wind turbine blades or fixed-wing aircraft can heavily affect the blade aerodynamics of rotorcraft. Using blade element theory, the pilot control inputs required to mitigate such vortex effects are estimated and compared to the available control margin at the operating condition of interest. In contrast, when no pilot action is performed, the rotor blade flapping caused by the vortex is evaluated and compared to available margins. It is a safety concern when the remaining margins become zero. The influence of the vortex strength, its core radius and orientation to the rotor disk are evaluated and the effect of rotor blade characteristics (Lock number, natural frequency) is investigated.

Analytic solution of in-plane vortex–rotor interactions with arbitrary orientation and its impact on rotor trim

“…Finally, because so far lateral vortex orientations were only computed by numerical simulation, e.g. [13][14][15], an example from [15] for V = − ∕2 is given in Fig. 5d for the collective, longitudinal and lateral control angles.…”

“…The analytic results for the longitudinal control angle in the case of V = ± ∕2 are shown here for the first time, so far they have been computed only numerically see [13][14][15]. An example from [15] is given in in Fig.…”

“…Although this kind of interaction will never be stationary and rather a transient process, the solution of the stationary interaction problem provides insight into the physics. This was solved only numerically in the past [13][14][15].…”